Viruses have been used to transduce genes of interest into mammalian cells for laboratory research and for clinical purposes. This approach has allowed expression and over-expression of proteins of interest as well as the understanding of both virus life cycles and eukaryotic cell mechanisms. Gene transduction used to treat genetic diseases, cancer, and more recently has been proposed as an approach to treat infectious diseases, vascular diseases and others disorders, e.g., Alzheimer's and Parkinson's disease. Viral vectors have been progressively modified in order to increase their transduction efficiency and to reduce their toxicity, immunogenicity and inflammatory potential. Limitations of gene expression systems include low or inadequate expression of the nucleic acid of interest or therapeutic gene.